Discontinuity a proof of antiquity, [69]

Discontinuous generic areas, [23]

Discontinuous areas, [64]

why rare, [64]

Dispersal of animals, [72]

of land animals, how effected, [73], [76]

along mountain-chains, [81]

of seeds by wind, [80], [257]

by birds, [81], [258]

by ocean-currents, [81], [258]